[fix](mtmv) Fix compensate union all wrongly when partition mv use partition external table (#52218)

Fix compensate union all wrongly when partition mv use partition
external table

in test mv/external_table/part_partition_invalid.groovy
order_qt_after_modify_data_and_refresh_catalog data should be as
following:
```
1	2	1	2023-10-17	2023-10-17
2	2	2	2023-10-18	2023-10-18
3	2	3	2023-10-19	2023-10-19
```


### What problem does this PR solve?

Issue Number: close #xxx

Related PR: #49514 

Problem Summary:

### Release note

None

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    - [ ] No need to test or manual test. Explain why:
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    - [ ] Yes. <!-- Explain the behavior change -->

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fe/fe-core/src/main/java/org/apache/doris/nereids/rules/exploration/mv/PartitionCompensator.java

@@ -85,8 +85,10 @@ public class PartitionCompensator {
         }
         MTMVPartitionInfo mvCustomPartitionInfo = mtmv.getMvPartitionInfo();
         BaseTableInfo relatedPartitionTable = mvCustomPartitionInfo.getRelatedTableInfo();
-        if (relatedPartitionTable == null || queryUsedBaseTablePartitionNameSet.isEmpty()) {
+        if (relatedPartitionTable == null || queryUsedBaseTablePartitionNameSet.isEmpty()
+                || !relatedPartitionTable.isInternalTable()) {
             // if mv is not partitioned or query not query any partition, doesn't compensate
+            // in 2.1, external table should not compensate union all
             return Pair.of(ImmutableMap.of(), ImmutableMap.of());
         }
         Collection<Partition> mvValidPartitions = cascadesContext.getStatementContext()